IV. Biology: One generation of adults
matures
each year. Grubs overwinter up to a foot (0.3 m) or more below the soil
surface. They gradually make their way close to the surface during the
spring, and feed mainly on decaying plant matter and to a lesser
degree on roots. Larvae may leave their protected sites and crawl
on their backs to establish a new site elsewhere. The grubs
pupate
by May and adults emerge in early July and August. Eggs are laid in
soil
with decaying vegetation.

V. Injury: Like JB, adult GJB are
responsible
for the principal damage to peaches. Beetles feed on petioles, leaves
and
fruit, and a single adult can cause significant damage. Adults are
often
found in groups and take large chunks from the fruit. Fruit injury is
not
as common as that from JB, but does occur when populations are large.
Most
injury is seen in late July and August, and unlike injury from JB, can
occur on both green and ripening fruit.

VI. Monitoring: Traps are available for JB
and are somewhat effective for GJB, but are only effective for
monitoring
the initial adult emergence. Adults may be monitored by quietly moving
into the tree, jarring several branches, and observing how many fly
off.
Direct fruit counts are the most effective way of assessing damage.
Fruit
should be examined by the method outlined for other insects. Since
feeding
may be "clumped" or unevenly distributed, care should be taken in
looking
at a representative sample before making a spray decision. If feeding
exceeds
1/2 to 1 percent, then a treatment is justified.

This is taken primarily from a chapter by D. F.
Polk, H. W. Hogmire
and C. M. Felland on peach direct pests, reprinted with permission from
Mid-Atlantic
Orchard Monitoring Guide, published by NRAES, 152 Riley-Robb Hall,
Ithaca, New York 14853-5701. (607) 255-7654.
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